1. Field of the Invention
The present invention relates to compounds having analgesic and in some cases immunostimulant activity.
The present invention also relates to pharmaceutical compositions containing these compounds as active ingredient for alleviating or eliminating pain in mammals and/or stimulating the immune system in mammals and to methods of using said pharmaceutical compositions as analgesics and or immunostimulants.
2. Background Art
Several compounds falling within one or more of the general definitions as “derivatives of 3-aryl-3-hydroxy-2-amino-propionic acid amides, of 3-heteroaryl-3-hydroxy-2-amino-propionic acid amides, of 1-aryl-1-hydroxy-2,3-diamino-propyl amines, 1-heteroaryl-1-hydroxy-2,3-diamino-propyl amines” are known in the patent and scientific literature.
For example, United States Patent Application Publications US 2003/0153768; US 2003/0050299 disclose several examples of the above-mentioned known compounds. The N-acyl compounds of these references are said to be useful as N-acylsphingosine glucosyltransferase inhibitors, the amide and the reduced compounds are described as intermediates in their preparations.
Illustrative specific examples of compounds of these references are shown below:

The publication Shin et al. Tetrahedron Asymmetry, 2000, 11, 3293-3301 discloses the following compounds:

L-threo-PDMP and some other known compounds used in the methods of this invention are commercially available, in pure enantiomeric and racemic forms, as applicable, from Matreya, LLC Pleasant Gap, Pa.
U.S. Pat. Nos. 5,945,442; 5,952,370; 6,030,995 and 6,051,598, which are all related to each other as being based on same or related disclosures, describe compounds which are structurally similar to the known compounds shown above. The compounds of these U.S. patent references are said to be inhibitors of the enzyme glucosylceramide (GlcCer) synthethase.
A publication in Journal of Labelled Compounds & Radiopharmaceuticals (1996), 38(3), 285-97 discloses the compound of the formula

Published PCT application WO 01/38228 discloses
in connection with a chromatographic method.
Kastron et al. in Latvijas PSR Zinatnu Akademijas Vestis, Kimijas Serija (1965) (4), 474-7 disclose the following compound.

Significantly, according to the best knowledge of the present inventors none of the above shown prior art compounds are disclosed in the prior art to have analgesics or immunostimulants activity.